Page 27 - Python Data Science Handbook

Text Entry Shortcuts

While everyone is familiar with using the Backspace key to delete the previous char‐
acter, reaching for the key often requires some minor finger gymnastics, and it only
deletes a single character at a time. In IPython there are several shortcuts for remov‐
ing some portion of the text you’re typing. The most immediately useful of these are
the commands to delete entire lines of text. You’ll know these have become second
nature if you find yourself using a combination of Ctrl-b and Ctrl-d instead of reach‐
ing for the Backspace key to delete the previous character!

Keystroke Action
Backspace key Delete previous character in line
Ctrl-d Delete next character in line
Ctrl-k Cut text from cursor to end of line
Ctrl-u Cut text from beginning fo line to cursor
Ctrl-y Yank (i.e., paste) text that was previously cut
Ctrl-t Transpose (i.e., switch) previous two characters

Command History Shortcuts

Perhaps the most impactful shortcuts discussed here are the ones IPython provides
for navigating the command history. This command history goes beyond your cur‐
rent IPython session: your entire command history is stored in a SQLite database in
your IPython profile directory. The most straightforward way to access these is with
the up and down arrow keys to step through the history, but other options exist as
well:

Keystroke Action
Ctrl-p (or the up arrow key) Access previous command in history
Ctrl-n (or the down arrow key) Access next command in history
Ctrl-r Reverse-search through command history

The reverse-search can be particularly useful. Recall that in the previous section we
defined a function called square. Let’s reverse-search our Python history from a new
IPython shell and find this definition again. When you press Ctrl-r in the IPython
terminal, you’ll see the following prompt:

In [1]:
(reverse-i-search)`':
If you start typing characters at this prompt, IPython will auto-fill the most recent
command, if any, that matches those characters:

Keyboard Shortcuts in the IPython Shell | 9